1. Field of the Invention
This invention relates generally to perpendicular magnetic recording write heads for use in magnetic recording disk drives, and more particularly to a write head with a trailing shield.
2. Description of the Related Art
Perpendicular magnetic recording, wherein the recorded bits are stored in a perpendicular or out-of-plane orientation in the recording layer, is a promising path toward ultra-high recording densities in magnetic recording hard disk drives. The recording or write head in perpendicular magnetic recording disk drives includes a write pole for directing magnetic field to data tracks in the recording layer, and one or more return poles for return of magnetic flux from the recording layer. The write head may also include a trailing shield (TS) of magnetically permeable material that faces the recording layer and is spaced from the write pole by a nonmagnetic gap. The use of a TS separated from the write pole by a nonmagnetic gap slightly alters the angle of the write field and makes writing more efficient. The TS must be very short as measured in the generally perpendicular direction, i.e., perpendicular to the recording layer. This dimension is called the TS “throat height” (TH). However, it is difficult to reliably fabricate a TS to very small thicknesses. For that reason a nonmagnetic TS “bump” or pad may be located between the gap and a portion of the TS. The TS pad has a recessed front edge and allows the TS to have a TH shorter that the overall height of the remaining portion of the TS. A perpendicular magnetic recording write head with a TS and a TS pad is described in pending application Ser. No. 11/090456 filed Mar. 25, 2005, published as US2006/215314 A1, and assigned to the same assignee as this application.
It is difficult to precisely define the location of the recessed front edge of the nonmagnetic pad so as to control the TH of the TS. What is needed is a perpendicular magnetic recording write head, and an improved method for making it, that has a trailing shield with a nonmagnetic pad with a precisely defined throat height.